The use of benzoxazines (BOX) offers a number of advantages as compared to other thermosetting resins including relatively long shelf-life, molecular design flexibility, low cost, high glass transition temperature (Tg), high modulus, relatively low viscosities, good flame retardant properties, low moisture absorption, no by-products released during curing and very low shrinkage upon curing. Furthermore, benzoxazines are capable of being self-cured upon heating; i.e. there is no need for an additional curing agent. This combination of properties means benzoxazines are potentially attractive for use in aerospace applications.
The commercial use of pure benzoxazine matrices in high-performance composites is currently not well established. Several commercial systems of benzoxazine hybrid systems are available (usually benzoxazine-epoxy) but the epoxy negates some of the benefits brought by benzoxazines. Toughening of benzoxazine only systems was limited to the use of rubbers, modified benzoxazine monomers and low performance thermoplastics, but these also reduce the beneficial properties of benzoxazines, most notably the flexural and tensile modulus.